1. Field of the Invention
The present invention relates to an apparatus and method for ascertaining the position, velocity and direction of travel of a vehicle at a remote location and for transmitting such information to a network-based server using a wireless communication system.
2. Description of the Related Art
Various apparatus and methods for ascertaining the position of individual vehicles and for communicating that information to a user at a location remote from said vehicles are known in the art. For example, U.S. Pat. No. 5,043,736 to Darnell, et al., discloses a cellular position locating system for ascertaining the latitude and longitude of an individual or object at a remote location and transmitting such information to a base station using a portable hand-held remote unit. The portable unit includes a receiver circuit for use with a satellite navigation system, a microprocessor for analyzing coded signals, cellular phone and modem circuits for transmitting encoded signals to a base station and a time of day clock. The base station includes a computational system for decoding position data and a visual display device for presenting the remote unit map coordinates.
In U.S. Pat. No. 5,742,509, Goldberg, et al., discloses a personal tracking system integrated with a base station. The tracking system includes a remote unit that includes a location determination means, a microprocessor, a modem, and a communication means connected to the modem. The base station includes a computer with software and a modem. The remote unit and the base station communicate with one another through a communication link.
In U.S. Pat. No. 6,131,067, Girerd, et al., discloses a client-server computer network and the use of such a network to access remote sensors having associated position determination sensors. In one embodiment of the invention, a remote sensor transmits positioning data to a server where it is analyzed to derive the location of the remote sensor. The location so determined is then transmitted from the server to the client and is displayed at the client so that the user can identify the location of the remote sensor. Use of the Internet as the client-server computer network is disclosed, along with use of a web page at the server having means for the user to identify a particular remote sensor.
The available means with which to determine the position of a remote sensor, or of a plurality of remote sensors, can be improved upon. For instance, there is a need to reduce the elapsed time that is presently required of a user in determining the position of each vehicle of a fleet of vehicles—e.g., each rental car of a fleet of rental cars or each truck of a fleet of transportation trucks. The present invention improves upon the currently available means for determining the several positions of a plurality of remote sensors by combining a fully integrated remote positioning sensor with currently available high speed telecommunications networks. The fully integrated remote positioning sensor carries out all position determining calculations, including and desired differential corrections and auxiliary calculations, on-board at the remote location. This enables all position and tracking data to be readily available for continuous or intermittent transmission of said data to a network-based server for data-basing the positional information. The data-based information is then available, on demand, when a user accesses the server to view positional information with regard to one or a plurality of vehicles. This obviates the need for polling the remote vehicle and substantially reduces the time required to access the positional information.
The device is also configured to store data on-board at the remote location during periods that the device is outside the communication range of a wireless network, and to automatically transmit the stored data as soon as the device returns to within the communication range of the wireless network. This last feature permits a history of the vehicle route and speed, etc., to be preserved for periods in which the vehicle is outside the communication range of the wireless network.